Strabo Geography 11.14.13

[13] It is thought that the Araxes was given the same name as the Peneius by Armenus and his followers because of its similarity to that river, for that river too, they say, was called Araxes because of the fact that it “cleft” ¹ Ossa from Olympus, the cleft called Tempe. And it is said that in ancient times the Araxes in Armenia, after descending from the mountains, spread out and formed a sea in the plains below, since it had no outlet, but that Jason, to make it like Tempe, made the cleft through which the water now precipitates ² itself into the Caspian Sea, and that in consequence of this the Araxene Plain, through which the river flows to its precipitate ³ descent, was relieved of the sea. Now this account of the Araxes contains some plausibility, but that of Herodotus not at all; for he says that after flowing out of the country of the Matieni it splits into forty rivers ⁴ and separates the Scythians from the Bactrians. Callisthenes, also, follows Herodotus.

[13] It is supposed that Armenus and his companions called the Araxes by this name on account of its resemblance to the Peneius, for the Peneius had the name of Araxes from bursting through Tempe, and rending ( ἀπαοͅάξαι) Ossa from Olympus. The Araxes also in Armenia, descending from the mountains, is said to have spread itself in ancient times, and to have overflowed the plains, like a sea, having no outlet; that Jason, in imitation of what is to be seen at Tempe, made the opening through which the water at present precipitates itself into the Caspian Sea; that upon this the Araxenian plain, through which the river flows to the cataract, became uncovered. This story which is told of the river Araxes contains some probability; that of Herodotus ¹ none whatever. For he says that, after flowing out of the country of the Matiani, it is divided into forty rivers, and separates the Scythians from the Bactrians. Callisthenes has followed Herodotus.